Process for refining lubricating oil



March 25, 1952 B; C, BENEDl-r4 2,590,490

PROCESS-FOR REF'NING LUBRICATING OIL ATTORNEYS Patented Mar. 25, A1952 PROCESS FOR REFINING LUBRICATIN G OIL Bruce C. Benedict, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Application May 24, 194s, serial No. 28,810

6 Claims.

This invention relates to a process for renning lubricating oil. `In one of its more specific aspects it relates to a process for producing an improved lubricating oil. In a preferred emobdiment of this invention lubricating oil of improved properties is produced by a two-step refining process utilizing hydrogen iiuoride and a hydrocarbon solvent.

Lubricating oils of high quality have been manufactured from crude oil fractions having suitable boiling ranges by many processes, including sulfuric acid refining, aluminum chloride rening, and solvent extraction. In sulfuric acid or aluminum chloride processes, the treating reagents are consumed by reaction with the oil and are not economically recoverable from the resulting sludges. In solvent refining, the action is simply one of separating high quality lubricating ingredients from the crude oil, or removing the undersirable or low quality constituents; thus the yield of finished lubricating oil can be no greater than the proportion of lubricating oilgrade hydrocarbons in the raw material.

An object of this invention is to produce high quality lubricating oil in high yeld by a chemical process in which the refining agents are recoverable.

Another object is to provide a two step process for manufacturing an improved lubricating oil.

Another object is to combine advantageously into a process for manufacturing lubricating oil, theV treatment of an oil with hydrogen fluoride and a hydrocarbon solvent.

Other objects and advantages of this invention will be apparent to one skilled in the art from the accompanying disclosure and discussion.

`According, to vmy invention,in a rst step a lubricating oil stock is extracted with a hydrocarbon solvent and a hydrogen liuoride-rich phase from a second step; and in the second step a hydrocarbon solvent-oil mixture is treated with liquid hydrogen iiuoride. The above lubricating oil stock may if desired contain both light and heavy materials outside the lubricating oil boiling range which may be easily removed by such means as fractionation subsequent to the refin ing treatment.

In a preferred embodiment `of my invention a crude oil fraction having a suitable boiling range is extracted in step one with propane and a hydrogen fluoride-rich phase from a second step, the propane and oil passing countercurrently to the hydrogen fluoride phase. The propane used acts as a precipitating solvent for-the asphalt, and the hydrogen fluoride-rich phaseacts as a selective solvent for the asphalt and resins. Step two of the process is a reaction step wherein the propane-oil phase from the extraction step is treated with anhydrous liquid hydrogen nuoride, stirring vigorously. The effluent from step two is separated into an oil rich layer and a hydrogen fluoride-acid soluble oil layer, the latter mixture being injected back into the step one extratction process as one of the extractiva media. The oil rich phase, that is, the phase containing both oil and propane, is separated in such a manner that the propane is recycled to the countercurrent extraction step, and the oil 4is recovered as the process product.

By this process the molecules of least stability are removed from the oil by solvent action and hydrogen iuoride extraction leaving only those of more stable structure to be acted upon in the reaction zone by the hydrogen uoride. Thus, with the most unstable molecules such as asphalt, olenic materials, and some armoatics removed, the control of the reaction is improved, and it is no longer necessary to produce excessive reaction with the most reactive constituents in order to produce suicient reaction with the less reactive components. Since the most reactive portions of the oil have already been removed by extractive means, the activity of the hydrogen iiuoride is maintained better and with less consumption of the reagent. Another advantage is that the hydrogen fluoride layer from the reaction step With its dissolved hydrocarbons is countercurrently extracted in the extraction step with the oil-solvent mixture to remove any desirable oil which may be occluded mechanically or be in solution with the hydrogen fluoride. :At the same time the hydrogen fluoride extracts the asphaltic and resinous materials and especially the color bodies, giving an oil of improved appearance as well as improved viscosity index and stability.

Because the two treatments of the oil with hydrogen iiuoride are in separate zones, each may be maintained at its optimum operating temperature and contact time. Thus, the chemical treatment in the reactor may take place under conditions of elevated temperature and very vigorous agitation, whereas the extraction step may be carried out at lower temperatures commensurate with the amount of materials which must necessarily be removed by extraction and with the desired contact time.

' My process is not limited to treatment of one specific oil, but may be modied within the scope of the invention to adapt it to any type of lubricating oil or lubricating oil stock to be treated and to the products which are desired. For example, an oil may be reacted at a high temperature so that a large portion of it is dissolved in the hydrogen fluoride phase. This dissolved material may include asphaltic or resinous substances not already removed by the extraction step, most of the naphthenes, and a portion of the paraiiins. Separation of the oil-hydrocarbon solvent phase from this treatment gives an oil of the highest viscosity index obtainable from the particular charge stock. Cooling of the hydrogen fluoride phase will cause the less soluble of the extracted hydrocarbons to separate out, thus giving an additional oil product. If cooling is accomplished in steps and separation is made following each cooling step, several fractions of hydrogen fluoride-soluble oil may be obtained, ranging from oil of improved Viscosity index to that with a viscosity index less than the treated oil.

The extractive hydrocarbon solvent may be any solvent which preferentially dissolves the desirable components of the oil, and produces an oil-solvent mixture at operating ratios the density of which is less than that of the hydrogen fiuoride or the hydrogen fluoride with its dissolved components. This extractive solvent should also be non-reactive with the hydrogen uoride at operating temperatures. In general, a parafin hydrocarbon having from 2 to 6, but preferably 2 to 4, carbon atoms per molecule meets these requirements. One such solvent which has already been mentioned is propane; another is n-buta'ne.

In the following descriptions two methods of operating my process are specifically disclosed. It is understood, however, that while they are representative in general of my process, various minor changes may be made in adapting the process to the various conditions within the scope of this invention. The drawings are schematic iiow diagrams and are to be referred to in conjunction with the following discussion. Various additional valves, pumps, and other conventional equipment, necessary for the practice of this invention, will be familiar to one skilled in the art and have been omitted from these drawings for the sake of clarity.

In Figure l, oil to be treated is introduced to extraction zone I'I through line I0, propane is introduced through line I 2, and a hydrogen iiuoride-rich phase is introduced through line I3. It is preferred that at least a portion of the propane be introduced below the interface formed by the propane-oil phase and the hydrogen iiuoride-rich phase in suicient quantity and sufciently below the oil introduction point to give a withdrawn hydrogen fluoride-rich phase free from occluded unreacted (undissolved) oil. A suitable ratio of oil charge to propane is 1:3 to 1:12. The propane is either recycled propane from line Id which is passed through surge zone I6, or makeup propane introduced through line I1 and also passed through surge zone I6 or a mixture of both. The recycle propane may contain minor portions of hydrogen fluoride fronthe reaction step hereinafter described; however, this is not detrimental. Any suitable extraction equipment may be used such as a vertical column packed with Raschig rings, helices, or other similar packing, or a column containing bubble plates, baffles, etc. However, my process is not to be limited bythe specific type of extraction equipment and other apparatus used. The materials are charged to extraction zone l I at a temperature in the range of to 200 F., but preferably ata-bout F. The iiow of materials to the extraction zone is so controlled that the interface between the propane-oil phase and the hydrogen fluoride-rich phase may be Varied; however, the preferred level is slightly above the point Where the propane is introduced through line I2, as indicated by reference numeral I 8. Make-up hydrogen fluoride is introduced to extraction zone II through lines 22 and I5. A suitable extraction temperature is between 100 and 210 F. and preferably between 180 and 205 F.

The pressure within extraction zone II should be maintained slightly above the vapor pressure of the constituents to prevent vaporization and to maintain the constituents in substantially liquid phase. The solubility of the oil will vary with the pressure, thus control of the pressure is essential. The preferred pressure would be such that the constituents are maintained substantially in liquid phase, and not greater than about 1000 pounds per square inch gauge.

The oil rich phase from extraction zone II is withdrawn through line I9 and passed to reaction zone 20 where it is reacted with recycle hydrogen fluoride introduced through line 2l and/or make-up hydrogen fluoride introduced through line 22, at a temperature above that in the extraction zone and in the range of 100 to 500 F., but preferably at about 350 F. The recycle hydrogen fluoride may contain some propane which is not objectionable since the oil already contains propane. The amount of hydrogen iiuoride used may vary within the range of 0.05 to 5 volumes per volume of the oil rich phase, but preferably 1 volume is used per volume of oil and propane. The contact time for the materials in reactor I I is from 10 minutes to 5 hours, however, the preferred time is about 2 hours. Suitable means for mixing the constituents in reaction zone 20 is represented by stirrer 23, and a suitable means is used for maintaining the desired temperature, such as heater 24. Y

Eiiluent from reaction zone 20 is passed through line 26, cooling zone 21, and line 28 to separation zone 29. The hydrogen fluoride layer is withdrawn from separation zone 29 through line 30 and passed through cooling zone 3l and line 32 to separation zone 33. The hydrogenfluoride layer from separation zone 33 is removed through line 34 and passed to cooling zone 36 where its temperature is adjusted to that of the extraction zone II into which it is to be introduced. Fromthere it is passed through line I3 and introduced to extraction zone I I as described heerinabove. If it is desirable not to use separation zone 33, the hydrogen fluoride layer in separation zone 29 is withdrawn through line 31 and passed through line 34, cooling zone 33, and line I3 to extraction zone II. If desired, a portion of the HF phase from zone 29 may be withdrawn and passed along with the HF phase from zone 33 to the extraction zone II.

The oil layer from separation zone 29 is withdrawn through line 3B and pased to fractionation zone 39. Treated lubricating oil is recovered from zone 39 through line 40. Propane is recycled to surge zone I 5 from fractionation zone 39 through lines 4I and IIS. The oil layer from separation zone 33 is passed through line i3 to fractionation zone 44. Treated oil is recovered through line 46 and propane is recycled shrough lines 41 and I4 to surge zone I6. The P liduct Oils recovered thrgugh lines 40 and 46 may be freed from traces of propane in a steam stripping zone not shown and then alkali washed or clay treated to remove traces of hydrogen iiuo-` ride.

The hydrogen fluoride phase from extraction i zone II is removed through line 48 and passed to fractionation zone 49. Here the hydrogen fluoride is separated from the asphaltic and resinous materials and passed through line 2| to reaction zone 20. The asphalt and similar materials are removed from fractionation zone 49 through line 50. Traces of hydrogen fluoride may be removed from the asphaltic materials by azeotropic distillation with propane or by steam stripping.

Referring now to Figure 2 which is a second. embodiment of my invention the lines and zones serving the same purpose as those in Figure 1 are similarly numbered. Where it is necessary to minimize the equipment required for economic or other reasons, my process may be operated as shown by Figure 2 and as described hereinafter. For the sake of brevity, the reaction conditions will be omitted in this discussion since they are the same as those given for Figure 1.

The oil to be treated is introduced through line I0 to extraction zone II. Propane is introduced through line I2, and a hydrogen fluoride rich phase, hereinafter described, is introduced through line 35. The propane is obtained from surge zone I6 which is fed by lines I4 and I1. When desirable, make-up hydrogen fluoride is introduced through lines 22 and I5. A portion of the oil rich phase which also contains most of the propane is removed from extraction zone II through line I9 and passed to reaction zone 20. This zone is equipped with a stirrer 23 and a heater 24. Recycle hydrogen fluoride and make-up hydrogen fluoride are introduced to the reaction zone through lines 2l and 22, respectively. Eiliuent from reaction zone is passed through line 26, cooling zone 2'I, and line 35 to extraction zone I I. This effluent includes the hydrogen fluoride phase mentioned hereinabove. In Figure 1 the hydrogen fluoride phase and oil phase were passed to separation zones where the oil layers were removed and passed to fractionation zones, and only the acid phase was recycled to the extraction zone. In this embodiment the total'eiiluent from reactor 20 is introduced to extraction zone II, which thus serves the dual function of extraction column and phase separator. A highly simplied flow system is thus obtained.

The remaining portion of the oil rich phase in lextraction zone II is removed through uline 25 and passed to fractionation zone 39. Here the propane is removed through line 4I and recycled through line I4 to surge zone I6. The treated oil is removed from fractionation zone 39 through line 40. The hydrogen fluoride phase from extraction zone II is removed through line 48 and passed to fractionation zone 49. The hydrogen fluoride is separated and removed through line 2I to reaction zone 20. The asphaltic mate-` rials are removed through line 58.

Advantages of this invention are illustrated by the following example. The reactants and their proportions, and other specic ingredients are 6 one volume per hour of a 14.3 volume per cent residue, fraction from West Edmund crude oil and 8 volumes per hour of propane are charged to an extraction column at a temperature of presented as being typical and should not be construed to limit the invention unduly.

Example In a system similar to that shown in Figure 2,

F. A hydrogen iluoride-oil-propane stream is also injected as described hereinafter. The oil is extracted by the propane and hydrogen fluoride, the propane and oil passing countercurrently to the hydrogen fluoride, at a top column temperature of 202 F. Five volumes per hour of oil-propane mixture are removed from the column as a side stream and reacted with one volume per hour of hydrogen fluoride in a reaction chamber so designed that the average contact time is 2 hours, at a temperature of 350 F. The eiiluent from the reactor is cooled to F. and then injected back into the extraction column as mentioned hereinabove. A treated oil-propane mixture is removed from the top of the extraction column. After removal of the propane and traces of hydrogen fluoride from the oil, it has the following properties'as compared with the oil charge and with a portion of the same oil treated only with propane.

As may be seen by the above data, an oil of improved viscosity index is obtained. In addition the stability is improved as shown by the reduction in the carbon residue.

Although this process has been described and exemplified in terms of its preferred modications, it is understood that various changes may be made without departing from the spirit and scope of the disclosure and of the claims.

I claim:

l. A process for refining lubricating oil which comprises introducing a lubricating oil stock, a normal paraffin hydrocarbon solvent containing not more than 4 carbon atoms per molecule, and a hydrogen fluoride-rich phase from a reaction zone to an extraction zone wherein said oil is extracted at a temperature in the range of 100 to 210 F. and a pressure above the vapor pressure of the constituents with said solvent and said hydrogen fluoride-rich phase, removing said hy- Vdrogen fluoride-rich phase from said extraction zone, removing a solvent-oil phase from said extraction Zone to a reaction zone wherein it is reactedwith hydrogen fluoride at a temperature in the range of 300 to 400 F. and for a reaction time in the range of 10 minutes to 5 hours, separating effluent from said reaction zone intoa solvent-oil phase and a hydrogen fluoride-rich phase which latter is recycled to said extraction zone as aforesaid, and separating said solvent-oil phase from said extraction zone into solvent which is recycled to said extraction zone and treated oil which is recovered as a product of the process.

2. A process for refining lubricating oil which comprises introducing a lubricating oil stock and propane at a temperature in the range of 100 to 200 F., and a hydrogen fluoride-rich phase to troduced below the interface formed by the propane-and-oil phase and said hydrogen fluoriderich phase, extracting said oil with said propane and said hydrogen fluoride-rich phase at a temperature in the range of 100 to 210 F. and a pressure above the vapor pressure of the constituents, said oil and said propane passing countercurrently to said hydrogen fluoride-rich phase, removing said hydrogen fluoride-rich phase from said extraction zone and separating hydrogen uoride therefrom for recycle to a reaction zone, removing said propane-oil phase from said extraction zone to said reaction zone wherein it is reacted with hydrogen fluoride in a proportion of 0.05 to volumes of hydrogen fluoride to one volume of propane and oil at a temperature in the range of 300 to 400 F. and a reaction time in the range of minutes to 5 hours, separating effluent from said reaction zone into a propaneoil phase and a hydrogen fluoride-rich phase, said hydrogen fluoride-rich phase being recycled to said extraction zone as aforesaid, separating said propane-oil phase from said reaction zone into propane and treated oil, recycling said propane to said extraction zone and recovering said treated oil as a product of the process.

3. A process for refining lubricating oil which comprises introducing to a vertical extraction zone a lubricating oil stock and propane at a temperature of about 180 F., and a hydrogen fluoride-rich phase at the temperature of said extraction zone at the point or introduction, at least a portion of said propane being introduced below the point of introduction of said oil and below the interface formed by the propane-andoil phase and said hydrogen fluoride-rich phase,

extracting said oil with said propane and said hydrogen fluoride-rich phase at a temperature in the range of 180 to 205 F. and a pressure above the vapor pressure of the constituents and not above about 1000 pounds per square inch gauge, said oil and said propane passing countercurrently to said hydrogen fluoride-rich phase, removing said hydrogen fluoride-rich phase from a low point of said extraction zone, separating same into a hydrogen fluoride fraction and an acid-soluble material fraction including asphalt, recycling thus separated hydrogen fluoride to a reaction zone, removing said propane-oil phase overhead from said extraction Zone to said reaction Zone wherein it is reacted in liquid phase with hydrogen fluoride in a proportion of propane and oil to hydrogen fluoride of about 1:1, at a temperature of about 350 F., and for about 2`hours, separating effluent from said reaction zone into a propane-oil phase and a hydrogen fluoride rich phase and passing said hydrogen fluoride-rich phase to said extraction zone as above described, separating said propane-oil phase removed from said reaction zone into propane and treated oil, recycling said propane to said vertical extraction zone, and recovering said treated oil as a product of the process.

4. A process for refining lubricating oil which comprises introducing a lubricating oil stock, a normal parafn hydrocarbon solvent containing not more than 4 carbon atoms per molecule, and a hydrogen fluoride-rich phase from a reaction zone to an extraction zone wherein said oil is extracted at a temperature in the range of 100 to 210 F. and a pressure above the vapor pressure of the constituents with said solvent and said hydrogen fluoride-rich phase, removing said hydrogen fluoride-rich phase from said extraction zone, removing a solvent-oil phase from said extraction zone to a reaction zone wherein it is reacted with hydrogen fluoride at a temperature in the range of 300 to 400 F. and a reaction time in the range of l0 minutes to 5 hours, passing effluent from said reaction zone back to said extraction zone wherein it is separated into a solvent treated oil phase and a hydrogen fluoriderich phase, recovering from said extraction said solvent-treated oil phase and separating same into solvent which is recycled to said extraction zone and treated oil which is recovered as a product of the process.

5. A process for refining lubricating oil which comprises introducing a lubricating oil stock and propane in a ratio of 1:3 to 1:12 and a temperature in the range of to 200 F., and a hydrogen fluoride-rich phase to an extraction zone wherein said propane is introduced below the interface formed by the propane and oil phase and said hydrogen fluoride-rich phase, extracting said oil with said propane and said hydrogen fluoride-rich phase at a temperature in the range of 100 to 210 F. and a pressure above the vapor pressure of the constituents, said oil and said propane passing countercurrently to said hydrogen fluoride-rich phase, removing said hydrogen fiuoride-rich phase from said extraction zone and separating hydrogen fluoride therefrom for recycle to a reaction zone, removing said propaneoil phase from said extraction zone to said reaction zone wherein it is reacted with hydrogen fluoride in a proportion of 0.05 to 5 volumes of hydrogen fluoride to one volume of propane and oil at a temperature in the range of 300 to 400 F. and a reaction time in the range of 10 minutes to 5 hours, passing efliuent from said reaction zone back to said extraction zone wherein it is separated into a solvent treated oil phase and a hydrogen fluoride-rich phase, recovering from said extraction said solvent-treated oil phase and separating same into solvent which is recycled to said extraction zone and treated oil which is recovered as a product of the process.

6. A process for refining lubricating oil which comprises introducing to a vertical extraction zone a lubricating oil stock and propane in a ratio of 1:3 to 1:12 and at a temperature of about 180 and a hydrogen fiuoride-rich phase at the temperature of said extraction zone at the point of introduction, at least a portion of said propane being introduced below the point of introduction of said oil and below the interface formed by the propane-and-oil phase and said hydrogen fluoride-rich phase, extracting said oil with said propane and said hydrogen fluoriderich phase at a temperature in the range of 180 to 205 F. and a pressure above the vapor pressure of the constituents and not above about 1000 pounds per square inch gauge, said oil and said propane passing countercurrently to said hydrogen fiuoride-rich phase, removing said hydrogen fluoride-rich phase from a low point of said extraction zone, separating same into a hydrogen fluoride fraction and an acid-soluble material fraction including asphalt, recycling thus separated hydrogen uoride to a reaction zone, removing said propane-oil phase overhead from said extraction zone to said reaction zone wherein it is reacted in liquid phase with hydrogen fluoride in a proportion of propane and oil to hydrogen fluoride of about 1:1, at a temperature of about 350 F., and for about 2 hours, passing effluent from said reaction zone back to said extraction zone wherein it is separated into a sol- 1 vent treated oil phase and a hydrogen fluoriderich phase. recovering from said extraction said UNITED STATES PATENTS solvent-treated oil phase and separating same Number Name Date DJO Solvent Which is recycled t0 Said Extraction 1,912,349 Tuttle May 3()J 1933 zone and treated oil which is recovered as a prod- 2,320,629 Matuszak June 1, 1943 ci ofthe DfOSS- 2,378,762 Frey June 19, 1945 BRUCE C- BENEDICT 2,425,559 passino et a1.. Aug. 12, 1947 REFERENCES CITED 2,454,615 Ridgway et a1. Nov. 23, 1948 The following refeijences are of record 1n the file of this patent: Y* l0 

1. A PROCESS FOR REFINING LUBRICATING OIL WHICH COMPRISES INTRODUCING A LUBRICATING OIL STOCK, A NORMAL PARAFFIN HYDROCARBON SOLVENT CONTAINING NOT MORE THAN 4 CARBON ATOMS PER MOLECULE AND A HYDROGEN FLUORIDE-RICH PHASE FROM A REACTION ZONE TO AN EXTRACTION ZONE WHEREIN SAID OIL IS EXTRACTED AT A TEMPERATURE IN THE RANGE OF 100 TO 210* F. AND A PRESSURE ABOVE THE VAPOR PRESSURE OF THE CONSTITUENTS WITH SAID SOLVENT AND SAID HYDROGEN FLUORIDE-RICH PHASE, REMOVING SAID HYDROGEN FLUORIDE-RICH PHASE FROM SAID EXTRACTION ZONE, REMOVING A SOLVENT-OIL PHASE FROM SAID EXTRACTION ZONE TO A REACTION ZONE WHEREIN IT IS REACTED WITH HYDROGEN FLUORIDE AT A TEMPERATURE IN THE RANGE OF 300 TO 400* F. AND FOR A REACTION TIME IN THE RANGE OF 10 MINUTES TO 5 HOURS, SEPARATING EFFLUENT FROM SAID REACTION ZONE INTO A SOLVENT-OIL PHASE AND A HYDROGEN FLUORIDE-RICH PHASE WHICH LATTER IS RECYCLED TO SAID EXTRACTION ZONE AS AFORESAID, AND SEPARATING SAID SOLVENT-OIL PHASE FROM SAID EXTRACTION ZONE INTO SOLVENT WHICH IS RECYCLED TO SAID EXTRACTION ZONE AND TREATED OIL WHICH IS RECOVERED AS A PRODUCT OF THE PROCESS. 